Thank you Sir. Much appreciated! I had not noticed that particular hammer. USFA and Long Hunter did a similar hammer profile as their version of a "turned down" race hammer. The Pietta hammer you have linked might well work in a USFA gun though.
I've made a couple of hammers by using a cut off Bisley hammer spur ( think the donor was a Ruger or Uberti hammer, can't remember) and a cut down USFA hammer, then welding the spur on.
I suspect you have seen them before. But here is the more traditional Bisley hammer spur that USFA made prior that I was looking for. Why? They allow you to see the sights after the hammer has dropped (which helps follow through) and they are easy to cock shooting one handed at paper. It makes a good hammer for a dedicated target gun.